US6567357B2 - Optical disk apparatus - Google Patents

Optical disk apparatus Download PDF

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Publication number
US6567357B2
US6567357B2 US09/839,522 US83952201A US6567357B2 US 6567357 B2 US6567357 B2 US 6567357B2 US 83952201 A US83952201 A US 83952201A US 6567357 B2 US6567357 B2 US 6567357B2
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Prior art keywords
surface deflection
jumping
recording medium
focus
optical disk
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US20010055254A1 (en
Inventor
Takashi Kishimoto
Yuuichi Kuze
Kenji Fujiune
Takeharu Yamamoto
Katsuya Watanabe
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Panasonic Holdings Corp
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Matsushita Electric Industrial Co Ltd
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Assigned to MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD. reassignment MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: FUJIUNE, KENJI, KISHIMOTO, TAKASHI, KUZE, YUUICHI, WATANABE, KATSUYA, YAMAMOTO, TAKEHARU
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/085—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam into, or out of, its operative position or across tracks, otherwise than during the transducing operation, e.g. for adjustment or preliminary positioning or track change or selection
    • G11B7/08505—Methods for track change, selection or preliminary positioning by moving the head
    • G11B7/08511—Methods for track change, selection or preliminary positioning by moving the head with focus pull-in only
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B2007/0003—Recording, reproducing or erasing systems characterised by the structure or type of the carrier
    • G11B2007/0009—Recording, reproducing or erasing systems characterised by the structure or type of the carrier for carriers having data stored in three dimensions, e.g. volume storage
    • G11B2007/0013—Recording, reproducing or erasing systems characterised by the structure or type of the carrier for carriers having data stored in three dimensions, e.g. volume storage for carriers having multiple discrete layers

Definitions

  • the present invention relates to an optical disk apparatus for optically reproducing information recorded on a recording medium by utilizing a light beam from a light source such as a laser.
  • the present invention relates to focus jumping control for moving a light beam spot from a recording/reproducing surface to another recording/reproducing surface on a recording medium having a plurality of recording/reproducing surfaces.
  • an optical disk apparatus conducts focus control by moving a converging lens in a direction substantially vertical to a recording/reproducing surface of a recording medium with a focus actuator.
  • the focus actuator is composed of a movable part and a fixed part attached to a converging lens.
  • the movable part and the fixed part are bound to each other via four wires or an elastic substance such as rubber.
  • the direction substantially vertical to the recording/reproducing surface refers to a vertical direction and a direction containing a slight deflection from the vertical direction. Furthermore, in the case where a recording/reproducing surface on which focus control currently is conducted is not a desired one, search for a desired information track on a recording medium having a plurality of recording/reproducing surfaces is conducted by repeating focus jumping to an adjacent recording/reproducing surface a plurality of times to conduct focus control on a desired recording/reproducing surface, and searching for a desired track.
  • FIG. 9 is a block diagram showing a schematic structure of a conventional optical disk apparatus that conducts focus jumping by a conventional focus jumping method.
  • FIG. 9 shows a state of the optical disk apparatus during focus jumping.
  • the conventional optical disk apparatus includes a disk motor 102 for rotating an optical disk 101 with two recording/reproducing surfaces (L0 surface, L1 surface) at a predetermined rotation speed, an optical head 103 (composed of a light source such as a semiconductor laser, a coupling lens, a polarized beam splitter, a polarizing plate, a converging lens, a condensing lens, a dividing mirror, a photodetector, and the like (not shown)) for reproducing information from the optical disk 101 , and a traverse motor (not shown) for moving the entire optical head 103 in a direction vertical to a track of the optical disk 101 .
  • a light source such as a semiconductor laser, a coupling lens, a polarized beam splitter, a polarizing plate, a converging lens, a condensing lens, a dividing mirror, a photodetector, and the like (not shown)
  • a traverse motor (not shown) for moving the entire optical head
  • a light beam generated by a light source is collimated by the coupling lens, reflected from the polarized beam splitter, passes through the polarizing plate, and is converged by the converging lens. In this manner, a light beam spot with a focus point in a thickness direction of the optical disk 101 is formed. The light beam spot is radiated to the optical disk 101 that is rotated by the disk motor 102 .
  • Light reflected from the optical disk 101 passes through the converging lens, the polarizing plate, the polarized beam splitter, and the condensing lens, and is split into light beams in two directions by the dividing mirror.
  • One of the divided light beams is input to a focus control apparatus through a photodetector with a two-division structure.
  • the focus control apparatus is composed of a focus error signal generating part 104 , a digital signal processor (DSP) 901 as a focus control part, a focus driving circuit 111 , and a focus actuator (not shown).
  • the focus error signal generating part 104 is provided as a converged state detecting part for generating a signal corresponding to a converged state of a light beam.
  • an output signal from the two-division photodetector is input to a differential amplifier.
  • An output signal from the differential amplifier becomes a positional shift signal (focus error (FE) signal) representing a shift between a converged point of a light beam and the optical disk 101 , and is input to the DSP 901 .
  • the detection of the FE signal is called an “SSD method”.
  • the FE signal input to the DSP 901 is converted from an analog signal to a digital signal by an AD converter 105 , and is input to a compensating filter 107 , which is a digital filter composed of an adder, a multiplier, and a delay circuit, through a switch 106 .
  • the compensating filter 107 compensates for a phase and the like of a focus control system.
  • the FE signal with its phase compensated by the compensating filter 107 is input to an adder 109 through a gain switching circuit 108 that switches a loop gain of the focus control system.
  • a switch 114 is turned off during focus control.
  • the FE signal passing through the gain switching circuit 108 passes through the adder 109 as it is, is converted from a digital signal to an analog signal by a DA converter 110 , and is input to the focus driving circuit 111 .
  • the focus driving circuit 111 amplifies an output signal from the DSP 901 and converts its level in an appropriate manner, thereby driving the focus actuator. In this manner, the focus actuator is driven so that a light beam on the optical disk 101 takes a predetermined converged state, whereby focus control is realized.
  • the other light beam divided by the dividing mirror is input to a tracking control apparatus (not shown) via a photodetector with a four-division structure, which detects a signal representing a shift between a converged point of a light beam and a track on the optical disk 101 , i.e., a track shift signal (tracking error (TE) signal) for controlling a converged point of a light beam to scan a track on the optical disk 101 , and conducts tracking control based on the TE signal so that a converged point of a light beam scans a predetermined track on the optical disk 101 .
  • a structure and operation of the tracking control apparatus are not related to the description of the focus jumping method directly; therefore, the description thereof will be omitted.
  • the DSP 901 is provided with the switches 106 and 114 .
  • the switch 106 is turned on, and the switch 114 is turned off.
  • focus jumping the switch 106 is turned off, and the switch 114 is turned on.
  • the switch 106 opens/closes a loop of the focus control system, and switches between an input signal during focus control and an input signal during focus jumping with respect to the compensating filter 107
  • FIG. 10 is a waveform diagram showing a FE signal and a focus driving waveform during focus jumping from the L0 layer to the L1 layer of the optical disk 101 .
  • the polarity of the FE signal and the focus driving waveform become inverse to that of the waveforms shown in FIG. 10 . Therefore, the waveform diagram and description thereof in this case will be omitted.
  • the switch 106 is turned off during focus jumping, and the compensating filter 107 is operated at an input zero. Therefore, the FE signal passing through the gain switching circuit 108 holds a low-pass component (surface deflection component) at the beginning of focus jumping.
  • the adder 109 adds an acceleration/deceleration pulse signal generated in an acceleration/deceleration pulse generating part 113 to the low-pass component at the beginning of focus jumping, which has passed through the gain switching circuit 108 .
  • the addition signal drives the focus actuator, whereby the instability of focus jumping caused by surface deflection of the optical disk 101 is reduced.
  • Step S 1101 the switch 106 is turned off, and the switch 114 is turned on (set a position for focus jumping).
  • Step S 1102 when an acceleration pulse (predetermined peak value Al) starts being output, the optical head 103 starts moving toward the L1 layer of the optical disk 101 , and an FE signal in a sine wave is generated in accordance therewith.
  • Steps S 1103 and S 1104 an acceleration pulse is output for a predetermined period of time (T 1 ), and the process waits until a zero crossing point (Z point in FIG. 10) of the FE signal is detected at Step S 1105 .
  • the zero crossing point is detected by detecting a crossing point between the FE signal passing through the AD converter 105 and a predetermined level (zero in this case) in the level detecting part 112 .
  • a deceleration pulse (predetermined peak value A 2 ) starts being output.
  • a deceleration pulse is output for a predetermined period of time (T 2 ).
  • the switch 106 is turned on, and the switch 114 is turned off (set at a position for focus control), whereby focus jumping to another recording/reproducing surface (e.g., from the L0 layer to the L1 layer) is completed, and focus control is restarted.
  • the conventional optical disk apparatus has a structure in which during focus jumping from a recording/reproducing surface to another recording/reproducing surface, a surface deflection component (shape of surface deflection) of the optical disk at the beginning of jumping is held, and a predetermined peak value, i.e., an acceleration/deceleration pulse are applied to the focus actuator for a predetermined period of time.
  • a surface deflection component shape of surface deflection
  • an object of the present invention to provide an optical disk apparatus that is capable of conducting high-speed reproduction with stable focus jumping performance by storing a surface deflection component (a surface deflection shape) in one rotation of an optical disk and starting focus jumping in the case where a positional change of a surface deflection component during focus jumping is a predetermined value or less.
  • a surface deflection component a surface deflection shape
  • Another object of the present invention is to provide an optical disk apparatus that is capable of conducting high-speed reproduction with stable focus jumping performance by storing a surface deflection component in one rotation of an optical disk and updating the surface deflection component held at the beginning of jumping during focus jumping, using the stored values.
  • the optical disk apparatus of the present invention for reproducing information recorded on a recording medium includes: a moving part for moving a converged point of a light beam converged on a recording medium having a plurality of stacked recording/reproducing surfaces in a direction substantially vertical to the recording/reproducing surfaces; a converged state detecting part for generating a signal corresponding to a converged state of the light beam on the recording medium; a focus control part for driving the moving part in accordance with a focus error signal that is an output signal from the converged state detecting part, in such a manner that the light beam is converged at a substantially constant position on the recording medium; a focus jumping part for moving the converged point of the light beam from an arbitrary recording/reproducing surface of the recording medium to another recording/reproducing surface thereof; a surface deflection measuring part for measuring a shape of surface deflection of the recording medium; and a jumping starting part for operating the focus jumping part based on measurement results of
  • the optical disk apparatus of the present invention includes: a moving part for moving a converged point of a light beam converged on a recording medium having a plurality of stacked recording/reproducing surfaces in a direction substantially vertical to the recording/reproducing surfaces; a converged state detecting part for generating a signal corresponding to a converged state of the light beam on the recording medium; a focus control part for driving the moving part in accordance with a focus error signal that is an output signal from the converged state detecting part, in such a manner that the light beam is converged at a substantially constant position on the recording medium; a focus jumping part for moving the converged point of the light beam from an arbitrary recording/reproducing surface of the recording medium to another recording/reproducing surface thereof; a surface deflection measuring part for measuring a shape of surface deflection of the recording medium; a surface deflection storing part for storing the measurement results of the surface deflection measuring part in a memory successively on a predetermined phase basis over one rotation
  • the optical disk apparatus of the present invention can store a surface deflection component in one rotation of an optical disk and start focus jumping in the case where a positional change in the surface deflection component during focus jumping to another recording/reproducing surface is a predetermined value or less. Because of this, an optical disk apparatus capable of conducting high-speed reproduction with stable focus jumping performance can be provided.
  • a substantially vertical direction refers to a vertical direction and a direction containing a slight deflection from the vertical direction.
  • a substantially constant position of a light beam includes a slight deflection from a converged position.
  • FIG. 1 is a block diagram showing a structure of an optical disk apparatus of Embodiment 1 according to the present invention.
  • FIG. 2 is a waveform diagram for illustrating a method for storing a surface deflection component in the optical disk apparatus, showing a relationship among an FG signal, a surface deflection storage timing signal, and a compensating filter low-pass component.
  • FIG. 3 is a flow chart showing an algorithm for calculating focus jumping start timing in the optical disk apparatus.
  • FIG. 4 is a flow chart of focus jumping processing in the optical disk apparatus.
  • FIG. 5 is a flow chart showing an algorithm for calculating focus jumping start timing in an optical disk apparatus of Embodiment 2 according to the present invention.
  • FIG. 6 is a block diagram showing a structure of an optical disk apparatus of Embodiment 3 according to the present invention.
  • FIG. 7 is a flow chart of focus jumping processing in the optical disk apparatus.
  • FIG. 8 is a flow chart of focus jumping processing in an optical disk apparatus of Embodiment 4 according to the present invention.
  • FIG. 9 is a block diagram showing a structure of a conventional optical disk apparatus.
  • FIG. 10 is a waveform diagram showing a relationship between an FE signal and a focus driving waveform during focus jumping in the conventional optical disk apparatus.
  • FIG. 11 is a flow chart of focus jumping processing in the conventional optical disk apparatus.
  • FIG. 1 is a block diagram showing a structure of an optical disk apparatus of Embodiment 1 according to the present invention.
  • a focus jumping method in the optical disk apparatus of Embodiment 1 is realized by adding a surface deflection measuring part 115 , a surface deflection storage memory 116 , a timing calculating part (herein, provided as a jumping start part and a jumping timing calculation part) 117 , a disk motor control part 118 , and a disk motor driving circuit 119 to a DSP (herein, provided as a focus control part) 120 in the structure of the conventional optical disk apparatus shown in FIG. 9 .
  • the same components as those in the conventional method are denoted with the same reference numerals as those therein. Therefore, the description thereof will be omitted here.
  • components corresponding to the disk motor control part 118 and the disk motor driving circuit 119 also are provided. They are not related to the description of the focus jumping method directly, so that the description thereof will be omitted here.
  • a focus actuator is driven so as to follow surface deflection of an optical disk (recording medium) 101 , and a predetermined relative distance is kept between a recording/reproducing surface of the optical disk 101 and a converging lens. Therefore, the shape of surface deflection of the optical disk 101 can be determined as the position of the converging lens. Since the surface deflection of the optical disk 101 is a cyclic phenomenon that occurs at the same cycle as that of rotation of a disk motor 102 , the shape of surface deflection is measured by using a positional change of the converging lens in one rotation cycle of the optical disk 101 . The shape of surface deflection may be measured indirectly with a sensor provided in an optical head 103 .
  • Embodiment 1 assuming that a certain phase in one rotation of the optical disk 101 is assumed to be time zero, the shape of surface deflection at a phase (when a predetermined number of phases proceed from time zero) will be described using a time axis by replacing the shape of surface deflection by that at time T (required for a predetermined number of phases to proceed).
  • the surface deflection measuring part 115 measures values of a delay circuit of a low-pass filter (composed of a delay circuit, an adder and a multiplier) for extracting a low-pass component in a compensating filter 107 , and outputs measurement results to the surface deflection storage memory 116 .
  • a cut-off frequency of the low-pass filter is set at least so as to pass a rotation frequency of the optical disk 101 .
  • the surface deflection storage memory 116 stores the measurement results of the surface deflection measuring part 115 by synchronizing them with a rotation cycle of the disk motor 102 , using a signal (FG signal) for measuring the rotation speed of the disk motor 102 .
  • the timing calculating part 117 calculates focus jumping start timing at which stable focus jumping is possible, by using the values of the surface deflection component (shape of surface deflection) stored in the surface deflection storage memory 116 , and controls the opening/closing of switches 106 , 114 and generation of a pulse in the acceleration/deceleration pulse generating part 113 during focus jumping.
  • the surface deflection component shape of surface deflection
  • FIG. 2 illustrates a method for storing a surface deflection component in the surface deflection storage memory 116 .
  • FIG. 2 shows an FG signal, a surface deflection storage timing signal for detecting timing at which a surface deflection component of the optical disk 101 obtained by dividing the FG signal by two is stored, and output values (low-pass component) of the delay circuit of the low-pass filter in the compensating filter 107 .
  • FIG. 2 illustrates a method for storing a surface deflection component in the surface deflection storage memory 116 .
  • FIG. 2 shows an FG signal, a surface deflection storage timing signal for detecting timing at which a surface deflection component of the optical disk 101 obtained by dividing the FG signal by two is stored, and output values (low-pass component) of the delay circuit of the low-pass filter in the compensating filter 107 .
  • FIG. 3 is a flow chart showing an algorithm for storing a surface deflection component in the surface deflection storage memory 116 and calculating focus jumping start timing, using the values stored in the timing calculating part 117 .
  • FIG. 4 is a flow chart showing a focus jumping processing flow in the present embodiment.
  • One rotation time of the optical disk 101 is measured at Step S 301 .
  • the measurement is conducted by measuring a cycle of an FG signal from the disk motor 102 in the disk motor control part 118 .
  • Step S 302 output values of the delay circuit of the low-pass filter in the compensating filter 107 are measured in the surface deflection measuring part 115 , and the results thereof are stored in the surface deflection storage memory 116 .
  • the surface deflection storage memory 116 includes 24 memories, and stores the output values of the delay circuit successively from a memory 0 to a memory 23 at predetermined timing. Specifically, as shown in FIG.
  • the surface deflection storage timing signal obtained by dividing the FG signal (generated in 6 pulses in one rotation of the optical disk 101 ) by two is generated in the surface deflection storage memory 116 , and the output values of the delay circuit of the low-pass filter are stored successively from a memory 0 on a rising and falling basis of the surface deflection storage timing signal. More specifically, assuming that timing 0 is time zero, a value “a” is stored in a memory 0 at timing 0 (time zero), and a value “b” is stored in a memory 1 at timing 1 after ⁇ fraction (1/24) ⁇ th rotation time.
  • a ratio of time required for focus jumping to one rotation time is calculated based on one rotation time of the optical disk 101 measured at Step S 301 and the time required for focus jumping, whereby the number of timings (N) during focus jumping in 24 timings is calculated.
  • the time required for focus jumping is a fixed value that is set in accordance with the sensitivity of the focus actuator, energy applied to the focus actuator by an acceleration/deceleration pulse, and the like.
  • Step S 304 a variable “i” is initialized.
  • Step S 305 the maximum (Max (i)) and the minimum (Min (i)) of the values in the delay circuit of the low-pass filter stored from timing “i” to timing (N ⁇ 1) ahead of the timing “i” are obtained.
  • Step S 306 the difference (d(i)) between the maximum and the minimum is obtained.
  • Step S 307 d(i) is compared with a predetermined value (Jmplvl), and in the case where d(i) is below the predetermined value (Jmplvl), the timing “i” is set to be focus jumping start timing at Step S 308 . In the case where d(i) exceeds the predetermined value (Jmplvl), the timing “i” is not set to be focus jumping start timing.
  • Step S 309 the variable “i” is increased until determination is completed whether or not each timing “i” is registered as focus jumping start timing at Step S 310 .
  • the calculation of focus jumping start timing corresponds to calculation for every proceeding of a phase by ⁇ fraction (1/24) ⁇ th rotation of the optical disk 101 .
  • the predetermined value (Jmplvl) is a fixed value that is set in accordance with the sensitivity of the focus actuator and energy applied to the focus actuator by an acceleration/deceleration pulse, and is set to be a level at which stable focus jumping is possible.
  • Step S 401 the process waits until the rotation position of the optical disk 101 reaches the calculated focus jumping start timing in 24 timings synchronized with the rising and falling of the surface deflection storage timing signal.
  • Step S 402 the switch 106 is turned off, and the switch 114 is turned on (set at a position for focus jumping).
  • Step S 403 an acceleration pulse (predetermined peak value A 1 ) starts being output.
  • the optical head 103 starts moving toward the L1 layer of the optical disk 101 , and an FE signal in a sine wave appears in accordance therewith.
  • Steps S 404 and S 405 an acceleration pulse is output for a predetermined period of time (T 1 ).
  • T 1 a predetermined period of time
  • a deceleration pulse (predetermined peak value A 2 ) starts being output.
  • a deceleration pulse is output for a predetermined period of time (T 2 ).
  • the switch 106 is turned on, and the switch 114 is turned off (set at a position for focus control).
  • focus jumping to another recording/reproducing surface e.g., from the L0 layer to the L1 layer
  • focus control is restarted.
  • each component operated when the switch 106 is turned off, and the switch 114 is turned on (set at a position for focus jumping) constitutes a focus jumping part.
  • focus jumping start timing should be conducted only once before focus jumping is conducted for the first time after activation of the apparatus. Furthermore, focus jumping start timing may be calculated respectively, for example, in the vicinity of an inner periphery and an outer periphery in accordance with a radius position of the optical disk 101 , and the focus jumping start timing may be switched in accordance with the intended track during a search.
  • one rotation of the optical disk is divided by 24 , and the output values of the delay circuit of the low-pass filter at the respective timings are stored in 24 memories.
  • the division number is set so that at least two output values of the delay circuit are stored in the time required for focus jumping.
  • the output values of the delay circuit of the low-pass filter in the compensating filter 107 are used for measuring a surface deflection component.
  • the same effects can be obtained even when the values of the FE signal passing through the AD converter 105 are stored in the surface deflection storage memory 116 on a rising and falling basis of the surface storage timing signal.
  • a differentiator is provided in the DSP 120 , whereby the output signal from the low-pass filter in the compensating filter 107 or the FE signal passing through the AD converter 105 is differentiated, and an acceleration of a surface deflection component of the optical disk 101 is calculated.
  • the same effects as those described above can be obtained by storing the acceleration of a surface deflection component that is an output signal of the differentiator, calculating the timing at which a change in the acceleration in time required for focus jumping is a predetermined value or less, and starting focus jumping at the calculated timing.
  • a surface deflection component at a certain time has been described using a time axis, assuming that a certain phase in one rotation of the optical disk 101 is time zero.
  • the description of the surface deflection component is not particularly limited to a time axis.
  • the output values of the delay circuit of the low-pass filter in the compensating filter 107 or the values of the FE signal passing through the AD converter 105 are used for measuring a surface deflection component, and the values are stored in the surface deflection storage memory 116 on a rising and falling basis of the surface deflection storage timing signal, obtained by dividing one rotation of the optical disk 101 on a predetermined phase basis.
  • a phase at which the difference between the maximum and the minimum of the stored values between predetermined phases is a predetermined value or less is calculated, and focus jumping is started at the calculated phase.
  • stable focus jumping can be realized without being influenced by a time concept.
  • Embodiment 2 of the present invention will be described.
  • the structure of the optical disk apparatus of the present embodiment is the same as that of Embodiment 1 shown in FIG. 1 .
  • This structure can be realized by altering the calculation algorithm of focus jumping start timing in the timing calculating part 117 .
  • the focus jumping start timing calculation algorithm in the present embodiment will be described with reference to a flow chart in FIG. 5 as well as the block diagram in FIG. 1 .
  • Step S 501 a surface deflection component of the optical disk 101 is measured.
  • Step S 502 the measurement results are stored in the surface deflection storage memory 116 .
  • Step S 503 the number of timings (N) during focus jumping in 24 timings synchronized with rising and falling of the surface deflection storage timing signal is calculated.
  • Step S 504 a variable “i” is initialized. This processing is the same as that described in Embodiment 1. Therefore, the description thereof will be omitted.
  • Step S 505 the difference (d(i)) in output values of the delay circuit of the low-pass filter at timing “i” and at timing (N ⁇ 1) ahead of the timing “i” is obtained, which is caused by the influence of surface deflection of the optical disk 101 .
  • d(i) is compared with a predetermined value (Jmplvl), and in the case where d(i) is below the predetermined value (Jmplvl), the timing “i” is registered as focus jumping start timing at Step S 507 . In the case where d(i) exceeds the predetermined value (Jmplvl), the timing “i” is not registered as focus jumping start timing.
  • Step S 508 the variable “i” is increased until determination is completed whether or not each timing “i” is registered as focus jumping start timing at Step S 509 .
  • the calculation of focus jumping start timing corresponds to calculation for every proceeding of a phase by ⁇ fraction (1/24) ⁇ th rotation of the optical disk 101 .
  • the predetermined value (Jmplvl) is a fixed value that is set in accordance with the sensitivity of the focus actuator and energy applied to the focus actuator by an acceleration/deceleration pulse, and is set to be a level at which stable focus jumping is possible.
  • focus jumping start timing should be conducted only once before focus jumping is conducted for the first time after activation of the apparatus. Furthermore, focus jumping start timing may be calculated respectively, for example, in the vicinity of an inner periphery and an outer periphery in accordance with a radius position of the optical disk 101 , and the focus jumping start timing may be switched in accordance with the intended track during a search.
  • one rotation of the optical disk is divided by 24, and the output values of the delay circuit of the low-pass filter at the respective timings are stored in 24 memories.
  • the division number is set so that at least two output values of the delay circuit are stored in the time required for focus jumping.
  • the output values of the delay circuit of the low-pass filter in the compensating filter 107 are used for measuring a surface deflection component.
  • the same effects can be obtained even when the values of the FE signal passing through the AD converter 105 are stored in the surface deflection storage memory 116 on a rising and falling basis of the surface storage timing signal.
  • a surface deflection component at a certain time has been described using a time axis, assuming that a certain phase in one rotation of the optical disk 101 is time zero.
  • the description of the surface deflection component is not particularly limited to a time axis, as described above.
  • the output values of the delay circuit of the low-pass filter in the compensating filter 107 or the values of the FE signal passing through the AD converter 105 are used for measuring a surface deflection component, and the values are stored in the surface deflection storage memory 116 on a rising and falling basis of the surface deflection storage timing signal, obtained by dividing one rotation of the optical disk 101 on a predetermined phase basis.
  • a phase at which the difference between the stored value at a certain phase and the stored value at a phase ahead of the certain phase by predetermined phases is a predetermined value or less is calculated, and focus jumping is started at the calculated phase.
  • FIG. 6 is a block diagram showing a structure of an optical disk apparatus of Embodiment 3 according to the present invention.
  • the optical disk apparatus of the present embodiment can be realized by, with respect to the structure described in Embodiment 1 shown in FIG. 1, deleting the timing calculating part 117 and adding a surface deflection correcting part 601 for correcting a positional change in a surface deflection component due to the influence of surface deflection during focus jumping, based on the stored values in the surface deflection storage memory 116 and a switch 602 for inputting the output signal from the surface deflection correcting part 601 to the compensating filter 107 only during focus jumping.
  • the components corresponding to those in Embodiment 1 are denoted with the same reference numerals as those therein. Therefore, the description thereof will be omitted here.
  • Step S 701 the process waits until an arbitrary edge of rising or falling of the surface deflection storage timing signal shown in FIG. 2 is detected. In the present embodiment, since one rotation of the optical disk 101 is divided by 24, the process waits for at most ⁇ fraction (1/24) ⁇ th hour of one rotation.
  • Step S 702 timing “i” with respect to the detected edge is stored.
  • Step S 703 sub-routine processing is started for correcting a change in a surface deflection component in focus jumping. The sub-routine processing will be described later.
  • the main processing is as follows.
  • Step S 704 the switch 106 is turned off, and the switches 114 and 602 are turned on (set at a position for focus jumping).
  • Step S 705 when an acceleration pulse (predetermined peak value A 1 ) starts being output, the optical head 103 starts moving toward the L1 layer of the optical disk 101 , and an FE signal in a sine wave appears in accordance therewith.
  • Steps S 706 and S 707 an acceleration pulse is output for a predetermined period of time (T 1 ), and at Step S 708 , the process waits until a zero crossing point of the FE signal is detected.
  • a deceleration pulse (predetermined peak value A 2 ) starts being output.
  • a deceleration pulse is output for a predetermined period of time (T 2 ).
  • Step S 712 sub-routine processing is completed.
  • Step S 713 the switch 106 is turned on, and the switches 114 and 602 are turned off (set at a position for focus control).
  • focus jumping to another recording/reproducing surface e.g. from the L0 layer to the L1 layer
  • focus control is restarted.
  • the surface deflection correcting part 601 reads a memory stored value f(i) at the stored timing “i” from the surface deflection storage memory 116 , using an extracting part 601 a , and updates the values in the delay circuit of the low-pass filter in the compensating filter 107 , using the stored value f(i).
  • the compensating filter 107 functions as a converging position holding part. During focus jumping, the switch 106 is turned off, and the switch 602 is turned on. Therefore, an acceleration/deceleration pulse is applied to a component holding the memory storage value f(i).
  • Step S 715 While an acceleration pulse and a deceleration pulse are output in the main processing, when the subsequent edge (timing “i+1”) of the surface deflection storage timing signal is detected at Step S 715 , the surface deflection correcting part 601 updates “i” at Step S 716 . The process returns to Step S 714 .
  • a surface deflection component at a certain time has been described using a time axis, assuming that a certain phase in one rotation of the optical disk 101 is time zero.
  • the description of the surface deflection component is not particularly limited to a time axis.
  • the output values of the delay circuit of the low-pass filter in the compensating filter 107 or the values of the FE signal passing through the AD converter 105 are used for measuring a surface deflection component, and the values are stored in the surface deflection storage memory 116 on a rising and falling basis of the surface deflection storage timing signal, obtained by dividing one rotation of the optical disk 101 on a predetermined phase basis.
  • the output values of the delay circuit of the low-pass filter in the compensating filter 107 are updated by using a memory stored value with some gain added thereto, every time a predetermined number of phases proceed during focus jumping in the surface deflection correcting part 601 . Because of this structure, stable focus jumping can be realized without being influenced by a time concept. In the case of using the output values of the delay circuit of the low-pass filter in the compensating filter 107 for measuring a surface deflection component, the gain in the surface deflection correcting part 601 becomes 1.
  • Embodiment 4 of the present invention will be described.
  • the structure of an optical disk apparatus of the present embodiment is the same as that described in Embodiment 3 shown in FIG. 6 .
  • This structure can be realized by altering a correction method in the surface deflection correcting part 601 .
  • Step S 801 the process waits until an arbitrary edge of rising or falling of the surface deflection storage timing signal shown in FIG. 2 is detected. In the present embodiment, since one rotation of the optical disk 101 is divided by 24, the process waits for at most ⁇ fraction (1/24) ⁇ th hour of one rotation.
  • Step S 802 timing “i” with respect to the detected edge is stored.
  • Step S 804 using focus jumping start timing i and end timing j extracted in the extracting part 601 a , a stored value f(i) with respect to timing i and a stored value f(j) with respect to timing j in the surface deflection storage memory 116 , the surface deflection correcting part 601 calculates a linear approximate function that represents a change in a surface deflection component during focus jumping.
  • Step S 805 interrupt processing for correcting a change in a surface deflection component during focus jumping, using the above-mentioned formula, is started.
  • Step S 816 a surface deflection component is calculated by using the above-mentioned formula on a predetermined interrupt time basis, and the output values of the delay circuit of the low-pass filter in the compensating filter 107 are updated.
  • processing from setting of switches at Step S 806 to the end of an output of a deceleration pulse at Step S 813 is the same as that in Embodiment 3. Therefore, the description thereof will be omitted here.
  • the interrupt processing is completed at Step S 814 .
  • the switch 106 is turned on, and the switches 114 and 602 are turned off (set at a position for focus control).
  • focus jumping to another recording/reproducing surface e.g., from the L0 layer to the L1 layer
  • focus control is restarted.
  • a surface deflection component has been described using a time axis.
  • the description is not required to be limited to a time axis.
  • an optical disk apparatus capable of conducting high-speed reproduction with stable focus jumping performance can be provided by storing a surface deflection component in one rotation of an optical disk and starting focus jumping in the case where the positional change of a surface deflection component during focus jumping to another recording/reproducing surface is a predetermined value or less.
  • an optical disk apparatus capable of conducting high-speed reproduction with stable focus jumping performance can be provided by storing a surface deflection component in one rotation of an optical disk and updating the surface deflection component held at the beginning of jumping during focus jumping, using the stored values.

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US20040136279A1 (en) * 2003-01-13 2004-07-15 Andrew Koll Interpolation of optical disc verticaldisplacement information
US20060285449A1 (en) * 2005-06-20 2006-12-21 Yoshinori Tazaki Optical disk drive and method of controlling the same
US20070058509A1 (en) * 2005-09-15 2007-03-15 Hitachi, Ltd. Optical disc device
US20070159939A1 (en) * 2004-01-16 2007-07-12 Yoshihiro Kanda Repetitive control device and optical disc device
US20080025165A1 (en) * 2006-07-25 2008-01-31 Samsung Electronics Co., Ltd. Optical disc drive and control method thereof
US20100118668A1 (en) * 2008-11-07 2010-05-13 Hitachi Consumer Electronics Co., Ltd. Optical disk drive

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JP3665629B2 (ja) 2002-07-30 2005-06-29 株式会社東芝 光ディスク装置と光ディスク装置の外乱学習方法
CN100385523C (zh) * 2003-03-28 2008-04-30 上海乐金广电电子有限公司 多层光盘记录/播放装置中的层间移动控制方法及其装置
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KR100723523B1 (ko) * 2006-01-20 2007-05-30 삼성전자주식회사 포커스 레이어 점프 제어회로 및 상기 회로에서 사용하는포커스 레이어 점프 제어방법
KR20110080193A (ko) * 2010-01-05 2011-07-13 주식회사 히타치엘지 데이터 스토리지 코리아 광디스크 드라이브에서의 레이어 점프 제어 장치 및 방법

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US20100118668A1 (en) * 2008-11-07 2010-05-13 Hitachi Consumer Electronics Co., Ltd. Optical disk drive

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